Relative to a naturally aspirated engine of similar output power, a turbocharged or supercharged engine may exhibit a prolonged duty cycle and increased blow-by (i.e., pressurized combustion gas entering the crankcase via the piston rings). Therefore, specialized engine components and/or configurations may be provided for proper maintenance of the engine lubricant. For example, a positive crankcase ventilation (PCV) system of a turbocharged or supercharged engine may include one or more enhanced air/lubricant separators to limit loss of engine lubricant to the intake during high-load operation.
The prolonged duty cycle and increased blow-by in a turbocharged or supercharged engine may cause engine lubricant to aspirated rapidly through any breech of the crankcase—through an uncapped lubricant filling port or unseated dipstick, for example. In some cases, an unacceptable loss of engine lubricant may occur in just a few hours of high-load operation when a dipstick is left unseated. If the loss of engine lubricant goes undetected, significant engine damage may result.
The inventors herein have recognized the disadvantages noted above and have provided a series of approaches to address them. One embodiment provides a method for indicating whether a crankcase of an engine is breeched, the engine having a crankcase ventilation system (positive, road draft, or foul air). This example method comprises restricting a communication of the crankcase with atmosphere, acting to increase or decrease a crankcase pressure, and indicating whether the crankcase is breeched based on the crankcase pressure. Another example method comprises sensing a crankcase pressure component, and indicating whether the crankcase is breeched based on the crankcase pressure component, the crankcase communicating with atmosphere via a conduit, a restrictedness of the conduit responsive to one or more of a crankcase pressure and a signal from an electronic control unit of the motor vehicle. Still other embodiments provide more particular methods for indicating whether the crankcase is breeched, and example configurations that enable the various methods. The approaches described herein provide reliable detection of a breeched crankcase in boosted engines, thereby avoiding excessive lubricant loss and prolonging engine life.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the Detailed Description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined by the claims that follow the Detailed Description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.